Various foams for topical delivery of active pharmaceutical ingredients are known in the art. However, the application of these foam compositions, either stable foams or quick breaking foams, requires rubbing or application of shear force to collapse the foam structure and to spread the collapsed composition on the application site.
U.S. Pat. No. 6,126,920 discloses foam compositions containing water or alcohols which have a disadvantage of increased irritation. In addition, although the specifications of the mentioned patent disclose quick breaking foam compositions that minimize rubbing of the target site, the need for rubbing is not completely eliminated.
U.S. Pat. Nos. 6,730,288 and 7,029,659 are directed to pharmaceutical foam compositions comprising an aqueous solvent, making them unsuitable for lipophilic or hydrous sensitive therapeutically active agents.
There is a need to develop a foamable composition which is lipophilic and completely anhydrous that collapses at the application site without requiring rubbing or application of shear force.